The present invention relates to a rolling device for filter assembly machines.
Currently used filter assembly machines are normally fed by a cigarette manufacturing machine with a succession of double cigarette portions, which are cut in half transversely into two single portions. The single portions in each pair are then parted axially to define in between a gap into which is inserted a double filter which, together with the two single portions, forms a "group" of coaxial elongated elements which are joined together to form a double cigarette.
To form the double cigarettes, a projecting strip of gummed paper is fed on to each group, which strip is slightly longer than the double filter, is positioned centrally on the group, and is wound about the group inside a rolling device.
In general, known rolling devices comprise a rolling drum for successively feeding the groups and respective strips into a rolling channel defined by a fixed plate facing the outer surface of the rolling drum. The plate extends over a relatively small arc--normally of about 60.degree.--of the periphery of the rolling drum, and is detached from the drum by a distance approximately equal to but no greater than the diameter of the double filter. On contacting the plate and by virtue of the friction produced by the plate on one side and the outer surface of the drum on the other, each group is rolled about its axis, thus winding the strip about the double filter and part of the two single portions, and is fed along the rolling channel at a speed equal to half the surface speed of the rolling drum.
Known rolling devices of the aforementioned type present several drawbacks, mainly due to the continually increasing output capacity of filter assembly machines and, hence, continually increasing travelling speed of the groups, the single portions of which tend to break on contacting the input end of the fixed plate, and to spill tobacco as a result of the relatively high rolling speed (roughly 5000 rpm) of the groups as they are fed along the rolling channel.